The Effects of Differing Cognitive Task Demands on Whole-body Energy Metabolism and Cerebral Blood-flow: Modulation by Multivitamins/Minerals and Coenzyme Q10

Overview

When completing difficult tasks, the brain requires faster delivery of energy sources (oxygen and glucose) via the blood. There is evidence to suggest that some nutritional supplements may increase blood circulation in the brain which can result in improved task performance. The purpose of the study is to evaluate the effects of a multivitamin/mineral preparation (containing a range of vitamins and minerals as contained in commonly consumed multivitamin/minerals available off the shelf) in healthy females on cerebral (brain) blood flow and energy expenditure during cognitive task performance.

Vitamins, minerals and CoQ10, exert a number of physiological effects directly relevant to energy supply and metabolism. Therefore it is hypothesized that the nutritional interventions in this trial will facilitate brain metabolic substrate distribution and utilisation during demanding brain activities with a potential benefit on task performance. This pilot, double-blind, placebo controlled, 3-arm parallel groups trial will utilise two concomitant non-invasive techniques: * Near Infrared Spectroscopy (NIRS) and * Indirect Calorimetry (ICa). The NIRS will be utilised to measure the rate of delivery of metabolic substrates (via cerebral blood flow i.e. concentrations of total-haemoglobin) and oxygen extraction from the blood (concentration of deoxy-haemoglobin) in the frontal cortex of the brain during cognitive tasks. The ICa calculated from exhaled gas analysis will be utilised to quantify the overall 'energy' costs of performance of tasks in terms of oxygen uptake, carbon dioxide production, energy expenditure, and substrate (fat and carbohydrate) metabolism. Cognitive tasks of differing levels of difficulty will be utilised with the hypothesis that energy expenditure parameters and blood flow/oxygen extraction will increase with rising task demands, and that any treatment related effect will be more evident under conditions of increased neural activity. The effects on the above mentioned parameters of two multivitamin/multimineral preparations (MMP) will be compared to placebo subsequent to single dose administration (acute) and following daily administration over an eight week period (chronic). The nutritional interventions are expected to improve nutritional status and thereby facilitate energy supply and metabolism and to have positive impact on the study parameters. The effects of the nutritional interventions on nutritional status will be evaluated by measuring the plasma/serum concentrations of a selected subset of analytes. It is hypothesized that the nutritional status at baseline and after eight week supplementation period will have an impact on metabolic substrate conversion, oxygen utilisation, cerebral blood flow and cognitive performance.